Child morbidity and mortality is high in sub-Saharan Africa with some 4.5 million deaths annually among children aged <5 years and 175 deaths per 1000 live births compared to 6 deaths per 1000 in industrialized nations. The majority of the childhood mortality and morbidity is due to infectious diseases, notably diarrhea, pneumonia and malaria. These problems are associated with poverty, including insufficient and poor quality food resulting in a high prevalence of malnutrition. Indeed under-nutrition and growth faltering has been identified as an underlying cause of around 50% of the deaths associated with infectious diseases in children in this region. In our previous work we found a strong association between aflatoxin biomarker levels and growth faltering in West African children;in addition, there was evidence of altered immunity in individuals with high biomarker levels. Dietary exposure to this mycotoxin may therefore make a significant contribution to childhood morbidity and mortality. The first goal of this project is to characterize the contribution of mycotoxin exposure early in life (pre- and post-natal) to growth faltering and health outcomes. We will test for an association between biomarkers of aflatoxin exposure and intestinal permeability as a first test of whether aflatoxin may affect growth via this mechanism. Maize is the main dietary staple for over 50% of the population in West Africa and is frequently co-contaminated with aflatoxins and another class of mycotoxins, the fumonisins. A second project goal is therefore to validate fumonisin exposure biomarkers to permit an evaluation of the combined effects of aflatoxins and fumonisins on child growth. Finally we will conduct postharvest intervention studies on maize using low technology approaches to assess their effectiveness in reducing human exposure to these environmental toxins, including via maize-based weaning foods that contribute much to the mycotoxin burden in young children. Collectively these studies will collaboratively link with biomarker research in Project 1 and lay the groundwork for application of targeted chemoprevention strategies described in Project 4.